Backcountry Avalanche Forecast for Southern San Juan
CGS: Colorado Geological Survey
Issued: 03/30/2012 6:59 AM by Matt Steen

Highlights

Another day of warm temperatures will continue the concerns of wet avalanches for the South San Juan 
zone. The frozen upper snowpack will quickly soften with today's increasing temperatures. Triggering 
a wet loose or wet slab avalanche will be possible on steep slopes today. Persistent slabs remain a 
concern on steep, shady slopes above treeline in areas of the zone where the snowpack is shallow. The 
snowpack is deeper to the east near Wolf Creek Pass and persistent weaknesses are less of an issue.

Avalanche Danger

The avalanche danger for the Southern San Juan zone is MODERATE (Level 2) on NW-N-NE-E aspects near 
and above treeline, is more pronounced for portions of the zone that hold a shallower snowpack. The 
danger will increase to MODERATE (Level 2) on NW-N-NE aspects below treeline in the afternoon, when 
wet avalanches will be easier to trigger.. Elsewhere, the danger is LOW (Level 1).
	
Snow & Avalanche Discussion

Temperatures dropped below freezing overnight, but not enough for a hard freeze. This morning's 
snowpack will be cold and frozen, but will quickly melt when hit by direct sun and warm ambient air 
temperatures. Dust on snow will increase warming and melting of the snowpack. Observers near Wolf 
Creek Pass have spotted some recent wet loose avalanches (WL-N-R1D2). They started below cliffs on 
low elevation, northerly aspects. You will want to continually assess the local snow conditions and 
keep track of the changes as the day progresses. Wet, sloppy, or punchy snow conditions are good 
indictors of potential wet avalanche problems. A small ball of snow can begin rolling down hill and 
gain mass, initiating wet loose and wet slab avalanches. Avoid traveling on or under south through 
west aspects in the afternoon.

Areas of the zone with a shallower snowpack have buried persistent weak layers. It is difficult to 
trigger a deep avalanche on persistent weak layers, but if any slide breaks down to a deep weak 
layer, the avalanche will be large and destructive. The problem is most pronounced on northwest 
through north to east aspects near and above treeline, and where the snowpack is shallower.

Weather Discussion for 11,000ft 	Issued: 03/30/2012 12:36 PM by John Snook 	

Weak westerly flow continues with only a light freeze at best by Saturday morning. Winds gradually 
swing toward southwest on Saturday with record high March temperatures expected. A low pressure 
trough pushes into the West Coast on Sunday. Southwest flow gradually increases, which keeps 
temperatures warm, but increasing high cloudiness will knock high temperatures down by a few 
degrees. Low pressure approaches the state Sunday night. Computer forecast models indicate the low 
will close off and track across Northern New Mexico. Colder temperatures and precipitation arrive 
late Sunday night. The track of the low remains somewhat uncertain. At this time, the southern and 
central zones are favored for moderate snow, while the northern zones receive light snow. The 
precipitation ends Monday afternoon. Long-range forecasts indicate high pressure returns for the 
remainder of the work week.